Dark green color of stool can be related to diet, in addition, when the digestive tract bleeding, taking medication, etc. can also cause the above manifestations, you can consult the doctor to clarify the cause of the disease. 1. Diet: Under normal circumstances, the color of human stool is mainly affected by the metabolites of bilirubin, which appears yellowish brown. When the stool shows black-green color, it can be caused by eating, for example, consuming too much green vegetables containing chlorophyll, or consuming animal liver or blood clots, etc., which can lead to deepening of the color of the stool, showing black-green. 2. Gastrointestinal bleeding: If there is no such causative factor, we should also pay attention to the presence of intestinal inflammation, cirrhosis caused by rupture of varicose veins in the fundus esophagus, and other factors leading to gastrointestinal bleeding caused by deepening of the color of the stools. 3. Taking medicines: in daily life, taking medicines such as bismuth potassium citrate, iron and so on can also appear in the stool as black-green. There are many reasons for the color of stool, when the color and shape of the stool or bowel habits change, it should be taken seriously, and can be diagnosed by the gastroenterology department.